Carburetor



Patented July 3, 1928.

UNITED STATES' PATENT oFFlcE.

WILLIAH 8. GUTHBIE, OF TERRELL, TEXAS,IASSIGNOR T MARVEL CARBURETOR COM- PANY, 0F FLINT, MICHIGAN, A CORPORATION OF INDIANA.

CARBURETOR.

Application filed April 3,

This invention relates to carburetors for internal combustion engines, the primary object being to provide a carburetor which is not only capable of eilicient performance, but

which may also be built at less expense than others having a comparable efficiency.

The invention especially consists of certain details of construction shown in the drawings and more fully described and "pointed out in the claims.

y AFig 1 is a vertical section showing one embodiment of the inve tion. 'Fig 2 is a partial section on line 2- of Fig. 1,. Fig. 3 is a fragmentary section correspondingr to Fig. 1, the valve being closed. Fig. 4 is an enlarged fragmentary section showing the valve for controlling the normal supply of fuel from the float chamber. Fig. 5 is a view,` similar to Fig. 1, showing a modification. Fig. 6 is a fragmentary section corresponding to Fig. 5 and offset somewhat from the plane thereof. Fig. 7 is an enlarged section on line 7-7 of Fig-5.

Referring to Figs. 1 to 4 inclusive, the body 1 has a main fuel reservoir 2 in which a float 3 controls the fuel valve 4 to open and close the inlet passage 5 to which the liquid is conveyed in the usual manner,

The fuel inlet valve 4Min the present case a needle valve-in the embodiment shown is preferably guided at both ends so the valve will not get out of line with its seat and thereby impair the same, and it has two por- .ions of.' different diameters the smaller of which passes, preferably rather loosely, through the float 3 and in the present case ,fielding the latter; and a cross pin 10 or the equivalent is provided on the valve vsomewhat below the bottom` of the float. It will thus be apparent that the float mayhave ronsiderable tree movement to accommodate and vibrations and relieve the valve seat largely from shocks it would get if the float auf; valve were closely connected. The con-- xetion is exceedingly cheap (the use of rposed lasers or the like being elimied), and may be applied le devices .wier than carburetora. Y

"ille liquid flows out el' the` reservoir gh pa yages NW2d-10'@ to a chamsurrounds the upper and of the and thence thi' rh the open- 2 inamliier surf-r riding re Thr i l@ and a isertioiil and 1919. Serial No. 287,277.

removal of the bushing; when the latter is in proper position, it bears upon the seat 28, thus limitingthe flow to the restricted orifice 17, from which it finally passes by way of the passage 29 to the nozzles 30-31. The valve 22 is threaded in the bushing 25 to permit adjustment with respect to the seat 32. As a convenient means for preventing leakage, the collar'33, packing 34 and nut 35 may be employed, the object of the collar being to exclude the packing from the slot QP' The orifice 17 is 'somewhat larger than the orifice 19 and determines the maximum flow, whereas the latter determines the minimum flow; it is evident that by properly adjustu ing the valve in relationto the seat 32 any variation between maximum and minimum may be secured. In practice, the orifice 17 is calibrated to pass a trifle more fuel than is ordinarilyY needed to run the motor under normal conditions in warm'weather at low altitudes; likewise, the orifice 19 is calibrated to pass a trifle less fuel than is needed under the same conditions. Consequently, while a more precise adjustment may be readily attained by turning the valve 22, unskilled drivers or workmen are prevented from upsetting the adjustment to such an extent as to very materially impair BJ the running of the motor, Again, the. jets. 19 and 17 may be, calibrated, respectively for high and low altitudes, thus enabling the user to adjust the carburetor for an intermediate4 altitude without the possibility of upsetting the motor to a very objectionable degree.

ln Fig. 5, the bushing 25 is omitted. and

the calibrated orifice 36 supplies the maxiv mum'llow. A, construction having the jet in a bushing is preferred when the body is made of iron, the danger of rusting being ob'viated by making the bushing of 'mises or the lil removable bushing is also con veulenty or properly calibrstng the maximum there `me of the air bypasses the venturi throttle by entering the auxiliary f 4.1 through 'the port passes elle around te; auaand lili.

iliary nozzle 3() and mixing with fuel discharging from the jet 43 flows up to the passage 44 and out into the chamber 39 beyond the air intake side of the throttle through the orifices 45, one of which may be controlled by the needle valve 46. The mixture thus supplied through the orifices 45 is entirely too rich for combustion and requires air from the venturi to make it combustible. When the throttle is opened more for the intermediate speeds, as shown in dotted lines, air from the passage 37'will flow up the auxiliary air passage 47 and lean out the mixture. The air passage 47 is formed in the wall of the venturi so as to bypass the restricted portion thereof, and its outlet end is so positioned in respect to the throttle that it is directly subjected to the air pressure beyond the air intake side of the throttle when the latter is nearl closed for intermediate speeds. At high speed the nozzle 30 admits air to the passage 29 to check the flow of fuel which would otherwise be discharged from the nozzle 31.

When starting the motor, especially in cold weather, it is necessary to enrich the mixture; this I do by means of an auxiliary fuel passage 48 which connects the passage 44 with the chamber independently of the fuel outlets which lead from said chamber to the jets or nozzles 30-31- The passage 48 may be opened or closed by means of the tapered valve 49 having a port 50 adapted t6' connect both portions of the passage 48 when in open position, Fig. l, and also having a longitudinal groove arranged to vent the lower portion ot' said passage when the valve closed, Fig. Si, wherebj,'-'Y leakage of fuel diie to suction is avoided. A convenient 'nl' in piac of the valve 49 when des i rring to 5-67: The joint betweei ine cover 63 and the i'loat chamber is preferably made reasonahlr tight by having darts tit ciosely, or the joint vmay 'oe as bj.' a gasket 65 so Ytheair vent 66 De regulated to vary the air pressure .ie reservoir by the needle 'alve o7 and .ist 68 cr .Le port 66 may be calibrated par motor. '.lhen by drilling the body to a point above the fuel the chamber 2 from a point just e s lv open position of the i at 39 Fig. ti, it is eviessure ...n the tioat chainced at intermediate speeds ease the dow ot fuel from a, and thus provi/fte ieaner i wcuid whew-fisc te supplied to the engine. The shape and size of the passage 69 is such as to reduce the pressure in the reservoir to effect a proper mi'xture.

In this modification, also, the nozzle is replaced by an auxiliary passage in the form of a tube 78 positioned in an auxiliary fuel chamber 79. The tube 78 is secured in place at the upper end of the chamber 79, prefer- 'ably by means of the bushing 80 and set screw 81, and the lower end of this tube 78 extends down below the level of the fuel in the chamber 79 when the motor is idling. The bushing 8() has a calibrated orifice 82 through which fuel flows from the interior of the -tube upwardly to the auxiliary mixing chamber 8G and thence to the passage 45'; and air is admitted to the chamber 79 above the level of the fuel in the float chamber through a calibrated orifice 83, in a removable plug 84, Fig. 7. The orifice 83 may be drilled directly in the wall of the chamber 79 when the size for the motor is known. A port 85 open to the atmosphere admits air to the auxiliary mixing chamber 86, and is preferably provided with a needle valve 87 for adjustment purposes, it being observed that the outlet of the passage 86 is pret'- ably positioned in the same relation vto the throttle as are the ports 45 in Fig. l, and for the same reason.

Assuming that the engine is ruiming at the slowest speed, the air pressure in the chamber 79 is atmospheric, and the level of the fuel therein (and in the nozzle 31) is not lowered below th level of the fuel in the reservoir 2, since the gravity low from the latter is sutlicicnt to maintain the level. Therefore since the orifice 45 is then sub- `iccted to a high suction on account of its position beyond. the air intake side of the throttle valve. raw fuel passes up through the orifice 82 into the auxiliary mixing chamber 86 where it mixes with air from the port 85` and is finally discharged at a rapid rate through the passage 45 iiito the main suction passage. The orifice 83 is uiadc ot such size to restrict the admis1 sion of air to the chamber 79 at high engine speeds so that the oi'oper flow from the nozzle fil is then secured. it being understood that the air pressure in the auxiliary chamber 79, the passage 29 and the nozzie 3l at the high speeds falls considerably beu tow that of the atiiiospiiere.

in the particular type of carburetor shown in the drawings, the air pressure in the suction passage between the 'Venturi tube and the throttle will be atmospheric, or nearly so, when the throttle is in the idling position as shown in Fig. 5 by dotted lines. Tt therefore rfollows that the air pressure in the float chamber will atmospheric when idling the engine, because the giassage 89 is then inoocrative since it is open to the suc tion passage below throttle, and when i the throttle opening is increased to about the position shown in Fig. 6, the passage 69 is subjected to the strong suction beyond the throttle, and this causes the air pressure 1n the float chamber to fall belowd that of the atmosphere. This reduced pressure in the float chamber holds back the flow of fuel for the intermediate speeds of the engine. The valve 67 provides means for conveniently adjusting the air passage 66 to regulate the air pressure in the fioatchamber to effect a proper mixture. When the throttle is opened more widely the suction in the passage 69 becomes less effective and results in the rising of air ressure in the float chamber, which permits the fuel to flow more freely for greater power and speed. The needle valve 22 may be adjusted to effect a proper mixture for the higher speeds.

The atmospheric pressure in the ioat chamber as above described permits the fuel to fiow to the auxiliary chamber 79 by gravity When idling theengine, the air pressure in the chamber 79 then being atmospheric. The nozzle 31 is made to discharge the fuel quite freely when the engine speed is accelerating, its discharge including the fuel stored in the chamber 79, and this provides a desirably rich mixture while the chamber 79 is being emptied. The partial vacuum in the fioat chamber at intermediate speed prevents the nozzle 31 feeding fuel at its full capacity at this speed, and the needle valve 22 prevents the nozzle discharging at its full capacity at high speeds. The discharge capacity of the nozzle 31 is such as to supply the fuel freely from the chamber 79 to acn celerate the engine speed efficiently.

It will be understood that I may use the customary needle valve for controlling the flowcf the fuel from the float chamber when desired in combination with one or more other features of the invention, 'or I may sometimes prefer to use a fixed orifice or the like. This also appliesito the outlet .from the auxiliary air passage 41 in Fig. l--that is to say, that a single orifice 45 may be employed with a needle valve to control the passage of fluid through the same or a single calibrated orifice may sometimes be used without a' needle valve.

I, therefore, do not wish to be limited except as set forth in the following claims.

I claim 1. A carburetor having a body provided with a mixing chamber, means for supplying air tothe mixing chamber, a source of fuel supply, a fuel passage leading from said source of supply to sald mixing chamber, an adjustable member for controlling the flow of fuel from the `source of supply having a fuel passage, a valve adapted to be seated in said last mentioned fuel passage, said valve having a fuel passage through its ends permitting the flow of fuel when the valve is in closed position.

2. A carburetor having a body provided with a mixing chamber having meansI for supplying air thereto, a fuel reservoir, a fuel passage extending from said reservoir to said mixing chamber and an adjustable member arranged at the point of supply control- WILLIAM S. GUTHRIE. 

